The present invention relates to vessels for pressurised fluid systems and more particularly, but not exclusively, to vessels for the cooling systems of automotive vehicles.
It is necessary for vessels, such as bottles, in pressurised fluid cooling systems in vehicles to be occasionally filled with cooling fluid. The vessel is therefore normally provided with a removable pressure relief/sealing cap which closes a filling opening. An example of a pressure relief/sealing cap to which the invention relates is described in our UK Patent No. 2174797.
It is desirable to provide a vessel in which the cap provides a reliable seal to prevent leakage from the filling opening during normal use and also during removal of the cap for filling.